Each word in the Spanish language is either marked with a tilde, such as in está, or is not marked with a tilde, such as in casa. Therefore in order to learn the orthographic system in Spanish, it is imperative for the learner to become proficient at distinguishing the rationale behind words that are marked with a tilde from words that are not marked with a tilde.
In order to become proficient at distinguishing the rationale behind words that are marked with a tilde from words that are not marked with a tilde, learners experience the problem of being forced to spend a long period of time and expend a large amount of effort as they attempt to figure out how to apply the rule set for tilde placement for words in Spanish. This problem has been on going as long as the rule set has existed. Because the rules have been difficult to learn to apply, learners may spend several semesters or years practicing and carrying out drills that focus on learning the accentuation system of Spanish.